1. Field of the Invention
The present invention generally relates to a submarine apparatus and, more particularly, to a submarine apparatus provided along a submarine cable together laid on a seafloor.
The xe2x80x9csubmarine apparatusxe2x80x9d means an apparatus laid on a seafloor, such as a submarine repeating apparatus, a submarine branching apparatus, or a gain equalizer.
A submarine cable used for communication is laid on a seafloor so as to connect land to land in the distance. Submarine apparatuses, such as a submarine repeating apparatus, a submarine branching apparatus, and a gain equalizer, are provided along the submarine cable laid on the seafloor.
For convenience"" sake in explanation, a description will be given of a facility used to lay a submarine cable on a seafloor, and of an operation to lay a submarine cable on a seafloor.
As shown in FIG. 1, in an operation of laying a submarine cable, a submarine cable 50 and submarine repeating apparatuses 60 are loaded onto a submarine-cable laying ship 10 equipped with a linear cable engine device 20, a sheave 30, and a submarine-cable embedding machine 40. Then, the laying ship 10 moves in a direction A1 along a laying route so that the submarine cable 50 and the submarine repeating apparatuses 60 are drawn out from the laying ship 10 in a direction A2 so as to be laid on a seafloor 70.
As shown in FIG. 2A and FIG. 2B, the linear cable engine device 20 comprises a plurality of rubber tires 21-1 to 21-6 and 22-1 to 22-6 aligned horizontally in a direction X2-X1, and cable guides 27 and 28 opposing each other transversely in a direction Y1-Y2. The rubber tires 21-1 to 21-6 and 22-1 to 22-6 oppose each other vertically in a direction Z1-Z2, respectively. The rubber tires 21-1 to 21-6 and 22-1 to 22-6 are movable vertically, and are energized in directions nearing to each other by oil hydraulic mechanisms (conveniently represented by springy members in FIG. 2B) 25 and 26. The cable guides 27 and 28 are movable transversely, are energized in directions nearing to each other by oil hydraulic mechanisms (conveniently represented by springy members in FIG. 2B) 23 and 24. This linear cable engine device 20 installed inboard guides the submarine cable 50 and the submarine repeating apparatuses 60 drawn out from the laying ship 10, and tenses the submarine cable 50 drawn out from the laying ship 10.
The sheave 30 is provided on the stern of the laying ship 10, and guides the submarine cable 50 and the submarine repeating apparatuses 60 drawn out from the laying ship 10.
When the seafloor is at a shallow sea, the submarine-cable embedding machine 40 is submerged onto the seafloor, and is slid on the seafloor by being hauled by the laying ship 10 so that the submarine-cable embedding machine 40 digs a groove, leads the submarine cable 50 and the submarine repeating apparatuses 60 into the groove, and then fills up the groove. The submarine cable 50 and the submarine repeating apparatuses 60 are buried in the seafloor so that a fishing net etc. is not caught on the submarine cable 50 and the submarine repeating apparatuses 60. As shown in FIG. 3, the submarine-cable embedding machine 40 comprises a bell mouth 41 in front, and a plurality of rollers 42-1 to 42-n and 43-1 to 43-n aligned horizontally from the bell mouth 41 in a direction A2. The rollers 42-1 to 42-n and 43-1 to 43-n oppose each other in vertical directions, respectively. The rollers 42-1 to 42-n and 43-1 to 43-n are movable vertically, and are energized in directions nearing to each other by oil hydraulic mechanisms (conveniently represented by springy members in FIG. 2B) 44 and 45.
In the operation of laying a submarine cable, the submarine cable 50 and the submarine repeating apparatuses 60 are moved as follows. First, the submarine cable 50 and the submarine repeating apparatuses 60 are transferred in the laying ship 10, and are guided between the rubber tires 21 and 22 of the linear cable engine device 20, whereby the submarine cable 50 drawn out from the laying ship 10 is provided with a tension T. The submarine cable 50 provided with the tension T is guided by the sheave 30 out of the laying ship 10 into seawater down to a seafloor, and is laid on the seafloor.
In a case of a shallow sea, the submarine cable 50 drawn out from the laying ship 10 is guided along the bell mouth 41 into the submarine-cable embedding machine 40, as shown in FIG. 3, and then is guided by the rollers 42-1 to 42-n and 43-1 to 43-n into the groove dug in the seafloor by the submarine-cable embedding machine 40.
As described above, in the course of the submarine repeating apparatuses 60 being transferred in the laying ship 10 and being led out of the laying ship 10 into the seawater down to the seafloor to be laid thereon, the submarine repeating apparatuses 60 pass a plurality of curved portions, and also go in and through the linear cable engine device 20, go over the sheave 30, and finally go in and through the submarine-cable embedding machine 40.
The submarine repeating apparatuses 60 are required to be easy to lay, i.e., to have a structure that allows a smooth operation of laying a submarine cable free from interruptions. Specifically, the submarine repeating apparatuses 60 are required to have a structure that avoids getting caught in the course of the operation of laying a submarine cable.
Additionally, when the submarine repeating apparatuses 60 get caught in the linear cable engine device 20, it is executable to cope with the caught-up submarine repeating apparatuses 60, because the linear cable engine device 20 is placed on the laying ship 10. However, when the submarine repeating apparatuses 60 get caught in the submarine-cable embedding machine 40, it is difficult to handle the caught-up submarine repeating apparatuses 60, because the submarine-cable embedding machine 40 is undersea. Therefore, it is especially important that the submarine repeating apparatuses 60 do not get caught in the submarine-cable embedding machine 40.
In the above-mentioned operation of laying a submarine cable, the bell mouth 41 has a function of guiding the submarine cable 50 and the submarine repeating apparatuses 60 along a guiding surface 41b on the upper part of the bell mouth 41 into the submarine-cable embedding machine 40. The bell mouth 41 has so predetermined a shape that the submarine repeating apparatuses 60 do not get caught thereby as long as the submarine cable 50 and the submarine repeating apparatuses 60 slide on the guiding surface 41b of the bell mouth 41. Additionally, a roller 41a is provided at a corner of the lower part of the bell mouth 41. The roller 41a supports the submarine repeating apparatus 60 entering the bell mouth 41, and revolves as the submarine repeating apparatus 60 transfers so that the submarine repeating apparatus 60 enters the submarine-cable embedding machine 40 smoothly.
2. Description of the Related Art
FIG. 4 shows a conventional submarine repeating apparatus 80. The submarine repeating apparatus 80 comprises a cylindrical body 81 in the center incorporating electronic components and optical components, and conical boots 84 and 85 at both ends. The body 81 comprises cylindrical joint rings 82 and 83 overhanging at both ends of the body 81. Ends of arm portions 86 extending from the boots 84 and 85 are connected with the joint rings 82 and 83 by gimbal joints 87, respectively. A bellows 88 covers between the boot 84 and the joint ring 82, and a bellows 89 covers between the boot 85 and the joint ring 83. The boots 84 and 85 can be bent freely in any direction with respect to the body 81 so that the operation of laying a submarine cable can be performed smoothly.
The arm portions 86 are necessary for the boots 84 and 85 to be bent freely in any direction with respect to the body 81.
The submarine repeating apparatus 80 is as heavy as approximately 500 kg. One of the boots 84 and 85 alone is as heavy as approximately 50 kg.
As shown in FIG. 2A, the cable guides 27 and 28 of the linear cable engine device 20 are provided so as to prevent the boot 84 carried out from between the rubber tires 21-3 and 22-3 from bending right and left in the direction Y1-Y2.
A space 90 is formed between each of the bellows 88 and 89 and the arm portion 86. Therefore, when the boot 84 carried out from between the rubber tires 21-3 and 22-3 slides between the cable guides 27 and 28 through, followed by the bellows 88 arriving between the cable guides 27 and 28, the cable guides 27 and 28 crush the bellows 88, and intrude into the space 90. When the cable guides 27 and 28 intrude deep into the space 90, an end surface of the joint ring 82 collides with the cable guides 27 and 28 such that the submarine repeating apparatus 80 may troublesomely get caught in the linear cable engine device 20.
Also in the submarine-cable embedding machine 40, as shown in FIG. 3, the rollers 42 and 43 may bend and crush the bellows 88, and intrude into the space 90, and the end surface of the joint ring 82 collides with the rollers 42 and 43 such that the submarine repeating apparatus 80 may troublesomely get caught in the submarine-cable embedding machine 40.
In accordance with the recent increase in communications traffic, there has been a trend in the conventional submarine repeating apparatus 80 that the difference between the diameters of the body 81 and the boot 84 becomes larger so as to increase the likelihood of causing the above-mentioned troubles.
Additionally, when the seawater or the seafloor is in bad conditions, or when the laying ship 10 fails to properly control the submarine-cable embedding machine 40, the submarine cable 50 drawn out from the laying ship 10 into the seawater wavers so as to cause the submarine repeating apparatus 80 to waver unstably at a point immediately before entering the submarine-cable embedding machine 40 as indicated by a double dashed chain line in FIG. 3; thereby, the submarine repeating apparatus 80 departs from the guiding surface 41b of the bell mouth 41 as shown in FIG. 5. In FIG. 5, large gaps 200 and 201 are created between the guiding surface 41b of the bell mouth 41 and the submarine repeating apparatus 80. When the submarine repeating apparatus 80 wavers unstably and departs from the guiding surface 41b of the bell mouth 41 so as to create the large gaps 200 and 201 as shown in FIG. 5, the end surface of the joint ring 82 draws near to the roller 41a provided at the corner of the lower part of the bell mouth 41 of the submarine-cable embedding machine 40, and collides with this roller 41a, whereupon the gimbal joint 87 nips the roller 41a such that the submarine repeating apparatus 80 may troublesomely get caught at the bell mouth 41 of the submarine-cable embedding machine 40.
It is a general object of the present invention to provide an improved and useful submarine apparatus in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a submarine apparatus provided along a submarine cable which apparatus can avoid getting caught in the course of laying the submarine cable.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a submarine apparatus laid undersea by a submarine-cable laying device, the apparatus comprising:
a cylindrical body performing a signal processing;
a conical boot arranged at each of both ends of the body so as to fix an end of a submarine cable, a diameter of an end of the boot being smaller than a diameter of each of both ends of the body;
a gimbal joint provided on each of both ends of the body so as to support an end of an arm portion extending from the boot; and
a spacer mechanism provided between the body and the boot so as to occupy a part of a space therebetween.
According to the present invention, in the course of laying a submarine cable, the spacer mechanism bears a part of the submarine-cable laying device so as to prevent the part from entering deep into the space between the body and the boot.
Additionally, in the submarine apparatus according to the present invention, the spacer mechanism may include a plurality of circular spacers each having a central opening so as to be arranged loosely around the arm portion, each of the spacers having a diameter equal to or smaller than the diameter of each of both ends of the body.
According to the present invention, since the spacers are arranged loosely around the arm portion, the spacers can be moved in an axial direction of the arm portion, and can be inclined easily with respect to the arm portion. Thereby, the spacer mechanism puts no restriction to the bending of the boot with respect to the body.
The inclined spacers narrow the opening width of the space between the body and the boot, or partition the space into two spaces each having a narrowed opening width. These narrowed opening widths prevent the part of the submarine-cable laying device from entering deep into the spaces.
The inclined spacers form an oblique plane that makes it easy for the part of the submarine-cable laying device to get out of the spaces.
Besides, since each of the spacers has a circular shape, whatever diametrical direction the submarine apparatus is positioned around the axis thereof, the spacers 121 to 123 function correctly with respect to the part of the submarine-cable laying device.
Additionally, in the submarine apparatus according to the present invention, the spacer mechanism may include a plurality of circular spacers each having a central opening so as to be arranged loosely around the arm portion, the spacers having different diameters decreasing toward the boot, each of the diameters being equal to or smaller than the diameter of each of both ends of the body.
According to the present invention, the spacers arranged in the order of diameter form a gently inclined plane with respect to the arm portion, compared to the spacers having a same diameter.
Additionally, in the submarine apparatus according to the present invention, each of the spacers may have a rib around the central opening.
According to the present invention, the rib creates a gap between the adjacent spacers. The gap alleviates a friction between the adjacent spacers so that the spacers can be smoothly inclined.
Additionally, in the submarine apparatus according to the present invention, each of the spacers may comprise a pair of half members combined with each other.
According to the present invention, each of the spacers can be assembled easily by combining the pair of the half members.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.